netvsp & mana_driver - Improve failure identification & improve cleanup

[ben-zen]

Arc::<T>::into_inner() returns Some(T) or None, and a call to unwrap() that returned result will panic with no clear error message; in cases where all clones of an Arc will eventually have into_inner() called on them, the resource will eventually be de-reference-counted and ultimately released, but the clones of ManaDevice::inner are stored in Vports which need to be cleaned up before one of the expected terminal states of the ManaDevice is reached.

This change replaces .unwrap() with .expect() on both calls to extract ManaDevice::inner from its Arc, and adds a cleanup step to force the release of netvsp's retained Vport instances.

[Copilot]

Pull request overview

Improves diagnosability of rare shutdown/save failures in the MANA VF driver by adding explicit panic messages when Arc::into_inner() fails, and ensures netvsp drops packet-capture controls during endpoint teardown to help release retained vport references.

Changes:

• Replace unwrap() with expect() for Arc::into_inner(self.inner) in ManaDevice::{save,shutdown} to provide clearer failure identification.
• Clear pkt_capture_controls after disconnecting endpoints to force-drop any retained packet capture controls during teardown.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
vm/devices/net/mana_driver/src/mana.rs	Adds clearer expect() messages when unwrapping the device inner Arc during save/shutdown.
openhcl/underhill_core/src/emuplat/netvsp.rs	Ensures packet capture controls are dropped after endpoint disconnect to help release retained vport references.

[ben-zen]

We discussed in the team that it's odd that Vport holds an Arc<Inner> if it should also be cleaned up before shutdown(). I looked at converting that Arc<Inner> to a Weak<Inner> & the blast radius of that change is, though not small, not huge either.

If that's seen as worthwhile, I plan to bring it as a separate patch as this is a targeted set of changes that are worthwhile in of themselves.